Adsorption process for recovering adsorbable components from a multi-component gas stream

ABSTRACT

By the present invention a cyclic adsorption process is provided for recovering adsorbable components from a multi-component inlet gas stream. One or more of a plurality of fixed beds of solid adsorbent are contacted with the inlet gas stream so that adsorbable components contained therein are adsorbed on the bed or beds. Simultaneously, one or more other of the bed or beds are contacted with a heated regeneration gas stream so that previously adsorbed components which are easy to regenerate are desorbed therefrom into said regeneration gas stream and recovered and one or more additional beds are contacted with a cooling gas stream so that the bed or beds are cooled. The flow patterns of the inlet gas stream, the regeneration gas stream and the cooling gas stream are continuously changed or cycled so that the bed or beds just contacted with the inlet gas stream are contacted with the heated regeneration gas stream thereby desorbing easy-to-regenerate components therefrom, the bed or beds just contacted with the cooling gas stream are contacted with the inlet gas stream and the bed or beds just contacted with the heated regeneration gas stream are contacted with the cooling gas stream. Each of the beds is periodically contacted with a second heated regeneration gas stream so that previously adsorbed components which are difficult to regenerate are desorbed into the second regeneration gas stream and recovered thereby preventing the buildup of difficult-to-regenerate components on the beds.

United States Patent [191 i [1 1 3,733,775

Barrere, Jr. [4 1 May 22, 1973 ABSORPTION PROCESS FOR provided for recovering adsorbable components from RECOVERING ADSORBABLE a multi-component inlet gas stream. One or more of a COMPONENTS FROM A MULTL- plurality of fixed beds of solid adsorbent are contacted COMPONENT GAS STREAM with the inlet gas stream so that adsorbable components contained therein are adsorbed on the bed or beds. Simultaneously, one or more other of the bed or [73] Assignee: Continental Oil Company, Ponca beds are contacted with a heated regeneration gas [75] Inventor: Clem A. Barrere, Jr., Houston, Tex.

City, Okla. stream so that previously adsorbed components which [22] Filed July 14 1971 are easy to regenerate are desorbed therefrom into said regeneration gas stream and recovered and one or [21] Appl. No.: 162,462 more additional beds are contacted with a cooling gas stream so that the bed or beds are cooled. The flow 52 U.S. c1 ..55/28, 55/62 Patems the inlet gas stream the regenemfim gas 51 rm. Cl. ..B01d 53/04 gas Stream are 58 Field of Search ..55/28, 62, 74,.75, change-d Ycled the beds 5 5/179 208 387 208/310 tacted with the inlet gas stream are contacted with the heated regeneration gas stream thereby desorbing l [56] References Cited easy-to-regenerate components therefrom, the bed or beds just contacted with the cooling gas stream are UNITED STATES PATENTS contacted with the inlet gas stream and the bed or v beds just contacted with-the heated regeneration gas 21333133? 1351328 23223;: 53311311:3111:1111313311392273 tttttttt tttttttttttt wtth the cooling as steam- 3,355,860 12/1967 Amoldi ..5s/75 Each the beds is Perimficauy with a second heated regeneration gas stream so that previp Examine, Chm-1es NHart ously adsorbed components which are difficult to Atmmey ]oseph Kotarski, Henry H, Hutch, regenerate are desorbed into the second regeneration R b }3 C l Jrand G k L Floyd gas stream and recovered thereby preventing the buildup of difficult-to-regenerate components on the beds.

[57] ABSTRACT 21 Claims, 9" Drawing Figures By the present invention a cyclic adsorption process is PATENTEU W2 2 73 SHEET 5 UF 9 ATTORNEY PATENTEDH-RYZEW 3,733,775

CLEM A. EAPPEPE, (/2.

ZZWMIRW ABSORPTION PROCESS FOR RECOVERING ADSORBABLE COMPONENTS FROM A MULTI-COMPONENT GAS STREAM BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to an adsorp tion process for recovering adsorbable components from a multi-component gas stream, and more particularly, but not by way of limitation, to a cyclic adsorption process for efficiently recovering both difficult and easy-to-regenerate components from a gas stream, which process utilizes a plurality of fixed beds of solid adsorbent.

2. Description of the Prior Art Many continuous cyclic vapor adsorption processes for recovering desired components from a gas stream have been developed which utilize a plurality of fixed beds of solid adsorbent. Generally, one or more of the beds are utilized for adsorbing adsorbable components from the gas stream while the other beds are being regenerated. That is, the beds are successively contacted with the inlet gas stream so that adsorbable components contained therein are adsorbed by the adsorbent. During the time that one or more of the beds are being contacted with the inlet gas stream, the other beds are regenerated by contact with a heated regeneration gas stream which causes previously adsorbed components to be desorbed therefrom followed by contact with a cooling gas stream so that the beds are cooled preparatory to again contacting the inlet gas stream. The flow patterns of the various gas streams are continuously changed or cycled so that the bed or beds which have just contacted the inlet gas stream are contacted with the heated regeneration gas stream, the bed or beds which have just been contacted with the heated regeneration gas stream are contacted with the cooling gas stream, and the bed or beds which have just been contacted with the cooling gas stream are contacted with the inlet gas stream.

The term adsorbable components is used herein to mean those gas components which are capable of being adsorbed and regenerated or desorbed from a bed of solid adsorbent, both of the readily condensible and noncondensible types. For example, hydrocarbon compounds contained in natural gas streams are readily adsorbed by a variety of commercially available solid adsorbents, and may be desorbed therefrom. In addition, components such as ethane, ethylene, carbon dioxide, hydrogen sulfide, etc. commonly found in refinery gas streams may be adsorbed and desorbed from adsorbent materials.

Adsorption processes of the type described above are often utilized for adsorbing two or more adsorbable components from a multi-component gas stream. Commonly, one or more of the adsorbable components are difficult to regenerate as compared to the other components and the difficult-to-regenerate components are present in the gas stream in minor quantities as compared to the easy-to-regenerate components. For example, natural gas streams usually contain hydrocarbon compounds which are relatively easy to regenerate, such as methane, ethane, propane and butane, and hydrocarbon compounds which are relatively difficult to regenerate, such as pentanes and heavier hydrocarbon compounds with the easy-to-regenerate compounds making up the major portion of the gas streams.

Refinery gas streams usually contain a major portion of hydrocarbon compounds which are relatively easy to regenerate, such as ethane and ethylene, and a minor portion of hydrocarbon compounds which are relatively difficult to regenerate, such as heavy olefin hydrocarbon compounds. As contrasted with easy-toregenerate components, in order to regenerate a bed of adsorbent having difficult-to-regenerate components adsorbed thereon, the bed must be contacted with a heated regeneration gas stream at a relatively high temperature and flow rate and/or for a relatively long period of time.

In an adsorption process wherein a bed of adsorbent is contacted with a multi-component gas stream containing both difficult and easy-to-regenerate adsorbable components, all of the adsorbable components are adsorbed on the bed to some degree. The most difficult-to-regenerate components are adsorbed first followed by other adsorbable components in the order to their degree of difficulty to regenerate. For example, when an adsorbent such as activated carbon is contacted with a gas stream containing methane, ethane and propane, the propane is adsorbed first followed by the ethane, with the methane being adsorbed last. When the activated carbon is regenerated by contact with a heated regeneration gas stream, the adsorbed hydrocarbon compounds are desorbed in reverse order.

In applications where adsorption processes are utilized for recovering easy-to-regenerate components from multi-component gas streams, the presence of difficult-to-regenerate components in the gas streams caused serious problems. In order to adsorb a major portion of the easy-to-regenerate components in a gas stream, the cycle time, i.e., the time the gas stream is allowed to contact the adsorbent must be limited. This is because the difficult-to-regenerate components are adsorbed first, and with increasing contact time the quantity of difficult-to-regenerate components adsorbed increases, thereby reducing the capacity of the adsorbent for easy-to-regenerate components. Due to the limited cycle time, adequate regeneration of the adsorbent is difficult to achieve, and heretofore over a period of time, adsorbed difficult-to-regenerate components build up on the adsorbent reducing its capacity for easy-to-regenerate components and decreasing the effective life of the adsorbent.

By the present invention, an adsorption process for recovering adsorbable components from a multicomponent gas stream is provided wherein each of the adsorbent beds is periodically subjected to extensive regeneration by contact with a heated regeneration gas stream at a relatively high temperature and flow rate, or for a long period of time, or both, thereby preventing the buildup of difficult-to-regenerate components on the beds and bringing about the recovery of a high percentage of the adsorbable components contained in the gas stream.

SUMMARY OF THE INVENTION The present invention relates to an adsorption process for recovering adsorbable components from a multi-component inlet gas stream which comprises contacting one or more of a plurality of beds of solid adsorbent with the inlet gas stream so that adsorbable components contained therein are adsorbed on the bed or beds. One or more other of the beds are contacted with a heated regeneration gas stream so that previously adsorbed components which are easy to regenerate are desorbed therefrom into the regeneration gas stream, and the easy-to-regenerate components are recovered from the regeneration gas stream. One or more other of the beds are contacted with a cooling gas stream so that the beds are cooled preparatory to contacting the inlet gas stream. The flow patterns of the inlet gas stream, regeneration gas stream and cooling gas stream are continuously changed so that the bed or beds just contacted with the inlet gas stream are contacted with the heated regeneration gas stream thereby desorbing easy-to-regenerate components therefrom, the bed or beds just contacted with the cooling gas stream are contacted with the inlet gas stream and the bed or beds just contacted with the heated regeneration gas stream are contacted with the cooling gas stream. Each of the beds are periodically contacted with a second heated regeneration gas stream so that previously adsorbed components which are difficult to regenerate are desorbed therefrom into the second regeneration gas stream thereby preventing the buildup of difficult-toregenerate components on the beds, and the difficultto-regenerate components are recovered from the second regeneration gas stream.

It is, therefore, an object of the present invention to provide an adsorption process for recovering adsorbable components from a multi-component gas stream.

A further object of the present invention is the provision of an adsorption process wherein each of the adsorbent beds utilized is subjected to an extensive regeneration so that difficult-to-regenerate components are removed therefrom and the buildup of difficult-toregenerate components on the beds is prevented.

Another object of the present invention is the provision of an adsorption process for recovering adsorbable components from a multi-component gas stream wherein a high percentage of the adsorbable compo nents are recovered.

Other and further objects, features and advantages of the present invention will be apparent from the following description of presently preferred embodiments of the invention, given for the purpose of disclosure and taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a system which may be used for carrying out the process of the present invention in diagrammatic form,

FIG. 2 illustrates the gas stream flow patterns through the system of FIG. 1 during a first cycle,

FIG. 3 illustrates the gas stream flow patterns through the system of FIG. 1 during a fifth cycle,

FIG. 4 illustrates an alternate system for carrying out the process of the present invention in diagrammatic form,

FIG. 5 illustrates the gas stream flow patterns through the system of FIG. 4 during a first cycle,

FIG. 6 illustrates the gas stream flow patterns through the system of FIG. 4 during a fifth cycle,

FIG. 7 illustrates yet another system which may be utilized for carrying out the process of the present invention in diagrammatic form,

FIG. 8 illustrates the gas stream flow patterns through the system of FIG. 7 during a first cycle, and

FIG. 9 illustrates the gas stream flow patterns through the system of FIG. 7 during a fifth cycle.

DESCRIPTION OF THE PREFERRED EMBODIMENTS contained within vessels 16, 13, 2t) and 22 by means of valves 24, 26, 28 and 30 disposed in conduits 32, 34, as and 38 respectively. The conduits 32, 34, 36 and 38 are connected to the header 14 and to inlet connections disposed in the vessels 16, 18, 20 and 22 respectively.

Conduits 40, 42, 44 and 46 are connected to outlet connections in the vessels 1%, 13, 20 and 22 respectively, and a residue gas outlet header 48 is connected to the conduits 4t), 42, 44 and 46 by conduits 50, 52, 54 and 56 respectively. Valves S8, 60, 62 and 64 are disposed in the conduits 50, 52, S4 and 56. The header 48 is connected by a conduit 66 to a residue gas inlet header 68. The residue gas inlet header 68 is connected to the conduits 32, 34, 36 and 38 by conduits 70, 72, 74 and 76 respectively. Valves '78, 8t), 82 and 84 are disposed in the conduits 711, 72, 74 and 76.

An effluent gas outlet header 86 is provided connected to the conduits 40, 42, 44 and 46. Valves 88, 90, 92 and 94 are disposed in the conduits 4t), 42, 44 and 46 respectively. The header 86 is connected to a ballast tank 96 by a conduit 98, and a conventional upstream pressure controller 100 is disposed in the conduit 98. The outlet connection of the ballast tank 96 is connected to a conduit 102 having a conventional check valve 104 disposed therein.

A conduit 106 is connected to the ballast tank 96 and to the suction connection of a conventional gas compressor or gas booster 1118. The discharge connection of the gas booster 1113 is connected to the conduit 110 having a conventional downstream pressure controller 112 disposed therein.

A closed regeneration gas stream circuit for continuously regenerating one of the adsorbent beds contained within the vessels 16, 18, 20 and 22 is provided. The term closed circuit is used herein to mean a system of conduits, valves, pumps, etc., within which a gas stream is continuously recirculated without the continuous addition or removal of gas therefrom. A conventional gas stream heater 114 is included in the regeneration gas stream circuit having a heating coil 116 disposed therein. The outlet of the heating coil 116 is connected by a conduit 118 to a regeneration gas stream inlet header 120. The header 121) is connected to the conduits 32, 34, 36 and 38 by conduits 122, 124, 126 and 128 respectively. Valves 130, 132, 134 and 136 are disposed in the conduits 122, 124, 126 and 128. A regeneration gas stream outlet header 138 is provided connected to the conduits 40, 42, 44 and 46 by conduits 140, 142, 144 and 146 respectively. Valves 148, 15th, 152 and 154 are disposed in the conduits 140, 142, 144 and 146. The regeneration gas stream outlet header 138 is connected by a conduit 156 to a conventional gas stream cooler 158. A valve 160 is disposed in the conduit 156, and the outlet of the gas cooler 158 is connected by a conduit 162 to the inlet of a conventional gas-liquid separator 164. The liquid outlet of the separator 164 is connected to a conduit 166 having a conventional liquid level control valve 168 disposed therein. The gas outlet connection of the separator 164 is connected by a conduit 170 to a conventional gas booster 172. The discharge "connection of the gas booster 172 is connected by a conduit 174 to the inlet connection of a heating coil 116 disposed in the heater 114. A cooler and separator bypass conduit 176 is connected to the conduit 156 upstream of the valve 160 and to the conduit 170. A valve 178 is disposed in the conduit 176.

A closedcooling gas stream circuit is provided including a cooling gas stream inlet header 180 connected to the conduits 32, 34, 36 and 38 by conduits 182, 184, 186 and 188 respectively. Valves 190, 192, 194 and 196 are disposed in the conduits 182, 184, 186 and 188. A cooling gas stream outlet header 198 is provided connected to the conduits 40, 42, 44 and 46 by conduits 200, 202, 204 and 206 respectively. Valves 208, 210, 212 and 214 are disposed in the conduits 200, 202, 204 and 206. The header 198 is connected by a conduit 216 to a conventional gas cooler 218. The discharge connection of the gas cooler 218 is connected by a conduit 220 to the suction of a conventional gas booster 222. The conduit 110, previously described, is connected to the conduit 220. The discharge of the gas booster 222 is connected by a conduit 224 to the cooling gas stream inlet header 180.

OPERATION OF THE SYSTEM By the present invention as carried out in the system 10, the inlet gas stream is passed through one of the vessels 16, 18, 20 and 22 so that it contacts the adsorbent bed contained therein and adsorbable components which are'difficult to regenerate are adsorbed on the bed. The bed is continuously contacted with the inlet gas stream over a long cycle time and as a result, the residue gas stream produced contains .easy-toregenerate adsorbable components. The residue gas stream is passed through another of the adsorbent beds contained within the vessels 16, 18, 20 and 22 so that easy-to-regenerate components are adsorbed thereon and an effluent gas stream substantially free of adsorbable components is produced. The flow patterns of'the residue gas stream, the heated regeneration gas stream and the cooling gas stream are changed or cycled on a short cycle time so that the three beds not adsorbing difficult-to-regenerate components from the inlet gas stream are operated in a manner such that one of the beds adsorbs easy-to-regenerate components from the residue gas stream, one of the beds is contacted with a heated regeneration gas stream so that easy-toregenerate components are desorbed therefrom and the other bed is contacted with the cooling gas stream. After a predetermined number of short cycles, the adsorbent bed previously on the long cycle is subjected to extensive regeneration during the next short cycle by contact with a heated regeneration gas stream at a high temperature and flow rate. In addition, the flow patterns of the various gas streams are changed so that a different bed is contacted with the inlet gas stream dur-.

ing the next long cycle while the other three beds are operating on the short cycle. By periodically subjecting each of the adsorbent beds contained within the vessels l6, 18, 20 and 22 to an extensive regeneration, adsorbed difficult-to-regenerate components are removed therefrom, and the buildup of difficult-to:

regenerate components, on the adsorbent beds is pre vented. Further, the operation ofthree of the adsorbent beds on a short cycle allows the recovery of an increased quantity of easy-to-regenerate components contained in the inlet gas stream as compared to prior art processes.

Referring specifically to FIG. 2, the flow patterns of the various gas streams in the system 10 during a first cycle are shown. Let it be assumed that the adsorbent bed contained within the vessel 16 is contacting the inlet gas stream over the long cycle time and the adsorbent bed within the vessel 18 is contacting the residue gas stream from the vessel 16. The inlet gas stream is conducted to the system 10 by way of the conduit 12. From the conduit 12, the inlet gas stream passes by way of the header l4, conduit 32 and valve 24 into the vessel 16. The conduits 34, 36 and 38, and the valves 26, 28 and 30 serve to conduct the inlet gas stream to the vessels 18, 20 and 22 during subsequent cycles. While the inlet gas stream passes through the adsorbent bed contained within the vessel 16, difficult-to-regenerate components are adsorbed on the bed, and a residue gas stream consisting primarily of easy-to-regenerate components is produced. The residue gas stream exits the vessel l6.by way of conduits 40 and 50, and valve 58, and passes into the residue gas stream outlet header 48. During subsequent cycles, the conduits 42, 52, 44, 54, 46 and 56, and the valves 60, 62 and 64 serve similarly to conduct the residue gas stream to the header 48; From the header 48, the residue gas streamis passed by way of conduit 66 into the residue gas stream inlet header 68. Fromthe header 68, the residue gas stream is conducted by conduit 72, conduit 34, and valve into the vessel 18. During subsequent cycles the con duits 32, 70, 36, 74, 38' and 76, and the valves 78, 82 and 84 serve to conduct the residue gas stream into the vessels 16, 20 and 22. While passing through the vessel 18, the residue gas stream contacts the adsorbent bed contained'therein and easyto-rege nerate components are adsorbed on the bed thereby producing an effluent gas stream substantially free of adsorbable components. The effluent gas stream exits the vessel 18 by way of conduit 42 and valve and passes into the effluent gas stream outlet header 86. During subsequent cycles, the conduits 40, 44 and 46 and valves 88, 92 and 94 serve similarly. From the header 86, the effluent gas stream passes by way of conduit 98 into the ballast tank 96, the operation of which will be described fur- .124, 34, 128 and 38 and valves 130, 132 and 136 serve similarly during subsequentcycles when the adsorbent beds within the vessels 16, 18 and 22 are being regenerated. As the heated regeneration gas stream passes through the vessel 20, it contacts the adsorbent bed contained therein and causes previously adsorbed easyto-regenerate components to be desorbed from the bed into the regeneration gas stream. The regeneration gas stream containing desorbed easy-to-regenerate components exits the vessel 20 by way of conduit 44, valve 152 and conduit,144, and passes into the regeneration ing through the gas cooler l58 the easy-to-regenerate components are condensed, and the condensed components and remaining regeneration gas stream pass' by way of conduit 162 into the separator 164. The condensed components are separated from the regeneration gas stream in the separator 164, and are withdrawn therefrom by wayof conduit 166 and valve 168 from where they are conducted to storage facilities (not shown) or to a point of further processing. From the separator 164 the regeneration gas stream passes by way of conduit 170 into the suction of the gas booster 172. k v

If the easy-to-regenerate components are of the noncondensible type, the regeneration gas stream is passed from the header 138 into the bypass conduit 176 by way of conduit 156 and valve 178. The conduit 176 conducts the regeneration gas stream containing easyto-regenerate components to the conduit 170. The regeneration gas stream is then passed through gas booster-172 and into conduit 174,. Arportion of the regeneration gas is withdrawn from the system 10 as a product stream by way of conduit 177 connected to the conduit 174.

The remaining regeneration gas stream is passed to the suction connection of the gas booster 172. The gas booster 172 functions to raise the pressure of the regeneration gas stream so that it circulates through the regeneration gas stream circuit; From the gas booster 172 the regeneration gas stream is passed into the conduit 174 from where it is conducted to the heating coil 116 of the gas heater 1 14. The regeneration gas stream is heated to a desired temperature levetwhile passing through the heating coil 116 of the heater 114. From the heater 114, the heated regeneration gas stream is conducted back to the regeneration gas stream inlet header by the conduit 118.

Let it be assumed that the adsorbent bed within the vessel 22 is in the process of being cooled. As shown in FIG. 2, a cooling gas stream is passed from the cooling gas stream inlet header by way of conduits 188 and 38, and valve 196, into the vessel 22. During subsequent cycles when the adsorbent beds within the vessels 16, 18 and 20 are cooled, conduits 32, 182, 34, 184, 36 and 186, and valves 190, 192 and 194 serve to conduct the cooling gas stream into the vessels 16, 18 and 20. As the cooling gas stream passes through the vessel 22, it contacts the adsorbent bed contained therein, cooling the bed and heating the cooling gas stream. The heated cooling gas stream exits the vessel 22 by way of conduits 46 and 206, and valve 214, and passes into the cooling gas stream outlet header 198.

During subsequent cycles the conduits 40, 200, 42,.

202, 44 and 204 and the valves208, 210 and.2l2 serve similarly. From the header 198, the heated cooling gas stream passes by way of conduit 216 into the gas cooler 218. While the cooling gasstream passes through the' gas cooler 218, the heat removed from the adsorbent bed contained within thevessel 22 is removed from the passed by way of conduit 220 into thegas booster 222 which functions to circulate the cooling gas stream through the cooling gas circuit. From the gas booster 222 the cooling gas stream is conducted by the conduit 224 back to the inlet header 180.

As mentioned above, the flow patterns of the residue gas stream, the cooling gas stream and the heated regeneration gas stream are changed at the beginning of each short cycle, while the flow pattern of the inlet gas stream is changed at the beginning of each long cycle. As will be understood, a variety of cycle timesmay be used depending upon the particular gas stream being processed in the system 10, and other operating and design conditions. In order to present a clear understanding of the manner in which the flow patterns of the various gas streams passing through the system 10 are changed, the adsorbent bed and valve sequence for the system 10 through 10 short cycles is shown in Table I. Table l is based on a long cycle time equal to four short cycle times.

(TABLE I Continued) Tenth Cycle Ninth Cycle SlXth Seventh Eighth Cycle Cycle Cycle Fifth Cycle Third Fourth Cycle Cycle Second Cycle Flrst Cycle Valve Desorbing difficult-to-regenerate components :in vapor form Easy-to-regenerate components removed Referring now to FIG. 3, the flow patterns of the various gas streams passing through the system 10 are illustrated during the fifth short cycle. As shown in Table I, the inlet gas stream is passed through the adsorbent bed contained within the vessel 16 during the long cycle time (short cycles one through four) thereby causing difficult-to-regenerate components to be adsorbed on the bed. The flow patterns of the residue gas stream, the regeneration gas stream and cooling gas stream are changed during the first four short cycles so that the adsorbent beds within the vessels 18, 20 and 22 adsorb easy-to-regenerate components, the easy-toregenerate components are regenerated by contact with the heated regeneration gas stream, and the beds are cooled. At the beginning of the fifth cycle, the flow pattern of the inlet gas stream is changed so that it is passed through the adsorbent bed contained within the vessel 18 which adsorbed easy-to-regenerate components in the preceding short cycle. Referring still to FIG. 3, the inlet gas stream is passed by way of conduit 12 into the header 14. From the header 14, the inlet gas stream is passed into the vessel 18 by way of conduit 34 and valve 26. As the inlet gas stream is passed through the adsorbent bed contained within the vessel 18, difficult-to-regenerate components are adsorbed thereon thereby displacing previously adsorbed easyto-regenerate components therefrom. The residue gas stream containing easy-to-regenerate components exits the vessel 18 by way of conduit 42 and valve 60, and passes into the residue gas stream outlet header 48. From the header 48, the residue gas stream passes by way of conduit 66 into the residue gas stream inlet header 68 from where it is conducted to the vessel 22 by way of conduit 76, valve 84 and conduit 38. While passing through the adsorbent bed contained within the vessel 22, easy-to-regenerate components are adsorbed from the residue gas stream and the effluent gas stream produced exits the vessel 22 by way of the conduit 46 and valve 94, and passes into the effluent gas stream outlet header 86. From the outlet header 86, the effluent gas stream passes by way of conduit 98 into the ballast tank 96 and is removed from the ballast tank 96 by way of conduit 102.

As shown in Table l, the adsorbent bed contained within the vessel 16 is regenerated during the fifth cycle so that difficult-to-regenerate components adsorbed thereon during the first four cycles are removed therefrom. In order to effectively bring about the desorption of the difficult-to-regenerate components during the fifth cycle, the adsorbent bed is contacted with a regeneration gas stream of high flow rate and temperature as' compared to the flow rate and temperature of the regeneration gas stream used to desorb easy-toregenerate components from the adsorbent beds. This is accomplished in the system 10 by providing high capacity equipment in the regeneration gas circuit. That is, the gas cooler 158, gas separator 164, gas compressorl72,gasheaterll4andtheassociatedconduitsand valves are sized such that a regeneration gas stream of the high flow rate and temperature required is generated during the cycles that difficult-to-regenerate components are desorbed from an adsorbent bed. The adsorbent bed contained within the vessel 16 is contacted with the heated regeneration gas stream of high flow rate and temperature which is passed from the regeneration gas stream inlet header to the vessel 16 by way of conduits 122 and 32 and valve 130. As the heated regeneration gas stream contactsthe adsorbent bed contained within the vessel 16, difficult-toregenerate components are desorbed therefrom into the regeneration gas stream. The regeneration gas stream exits the vessel 16 by way of conduits 40 and 140, and valve 148, and is passed into the regeneration gas stream outlet header 138. From the header 138, the regeneration gas stream is passed by way of conduit 156 and valve 160 into the gas cooler 158. Difficult-toregenerate components contained in the regeneration gas stream are condensed in the gas cooler 158, and the regeneration gas stream and condensed components exit the gas cooler 158 by way of conduit 162, and pass into the separator 164. While within the separator 164,

the condensed difficult-to-regenerate components are separated from the regeneration gas stream, and are removed therefrom by way of conduit 166 and valve 168. From the separator 164, the regeneration gas stream passes by way of conduit 170 to the gas booster 172 and then by way of conduit 174 into the heating coil 116 of the gas stream heater 1.14. From the heater 114, the regeneration gas stream circulates by way of conduit 118 back to the regeneration gas stream inlet header 120.

During the fifth cycle, the adsorbent bed contained within the vessel 20 is cooled by contact with the cooling gas stream. The cooling gas stream is passed from the cooling gas stream inlet header 180 into the vessel 20 by way of conduits 186 and 36, and valve 194. While passing through the adsorbent bed contained within the vessel 20, the cooling gas stream cools the adsorbent bed, and exits the vessel 20 by way of conduits 44' and 204, and valve 212. The cooling gas stream then passes into the cooling gas stream outlet header 1 98, and into the gas stream cooler 218 by way of conduit 216 wherein it is cooled. The cooling gas stream exits the gas stream cooler 218 by way of conduit 220 and passes into the gas booster 222. From the gas booster 222, the cooling gas stream is circulated by way of conduit 224 back into the cooling gas stream inlet header 180.

As will be understood by those skilled in the art, as a bed of adsorbent is cooled by contact with a cooling gas stream confined within a closed circuit, a portion of the cooling gas stream is adsorbed on the bed. This reduces the volume of cooling gas circulated which in turn brings about a decrease in the cooling gas stream pressure. In order to maintain the pressure of the cooling gas stream at a relatively constant level, it is necessary to add a quantity of make up gas to the cooling gas stream. Because the process of the present invention brings about the recovery of a high percentage of the adsorbable components contained in the inlet gas stream, and quite often the inlet gas stream is comprised primarily of adsorbable components, the flow rate of the effluent gas stream withdrawn from the system 10 is relatively low. In fact depending upon the particular inlet gas stream processed, the rate of effluent gas produced may decrease to a very low flow'rate during each short cycle. Thus, if a constant volume of effluent gas is withdrawn from the system 10, the pressure level of the gas streams passing therethrough may be decreased drastically. In order to maintain the pressure level of the gas streams at a relatively constant level, and to insure that effluent gas is available as make up to the cooling gas stream circuit during each cycle, the ballast tank 96 is provided. In operation of the system 10, the upstream pressure controller 100 disposed in the conduit 98 is set to maintain the effluent gas within the header 86 at a constant pressure. The check valve 104 is provided in the conduit 102 so that effluent gas is withdrawn from the ballast tank 96 only when the pressure level therein exceeds the pressure downstream of the check valve 104. For example, the system may be operated at a pressure of 1,000 psia with the effluent gas stream produced being conducted to a distribution system operated at a pressure of 700 psia. Thus, as long as the pressure within the ballast tank 96 is above 700 psia, effluent gas will pass through the conduit 102 and check valve 104 into the distribution system. However, during periods when make up gas is being withdrawn from the ballast tank 96 and/or when the effluent gas produced by the system 10 decreases, the pressure within the ballast tank 96 may decrease to a level below 700 psia. The check valve 104 prevents the backflow of effluent gas from the distribution system in this event.

Make up gas is withdrawn from the ballast tank 96 by way of conduit 106 which is connected to a gas booster 108. The gas booster 108 functions to pump gas into the cooling gas stream circuit by way of the conduit 110 when the pressure controller 112 disposed in the conduit 110 is open. As will be understood, the pressure controller 112 is set at the desired cooling gas stream pressure level so that when the pressure of the cooling gas stream decreases, the controller 112 opens thereby causing make up gas to pass into the-cooling gas stream circuit.

Referring now to FIG. 4, an alternate system which may be used for carrying out the process of thepresent invention, generally designated by the numeral 230, is illustrated. The system 230 differs from the system 10 described above in that instead of adsorbing difficultto-regenerate components from the inlet gas stream over the long cycle, one of the adsorbent beds in the system 230 is subjected to extensive regeneration over the long cycle. The other beds are operated on a short cycle with each of the beds adsorbing both difficult-toregenerate and easy-to-regenerate adsorbable components from the inlet gas stream. The beds operated on the short cycle are partially regenerated so that easy-toregenerate components are desorbed therefrom during the short cycle, and as the beds operated on the short cycle become loaded with difficult-to-regenerate components, they are subjected to extensive regeneration on the long cycle.

A multi-component inlet gas stream containing adsorbable components is conducted to the system 230 by way of an inlet conduit 232. From the conduit 232, the inlet gas stream passes into an'inlet gas stream header 234 from where it is routed to one of four vessels 236, 238, 240 and 242, each containing a fixed bed of solid adsorbent. The inlet gas stream is conducted to one of the four vessels by means of conduits 252, 254, 256 and 258 which are connected to the header 234 and to inlet connections disposed in the vessels 236, 238, 240 and 242. Valves 244, 246, 248 and 250 are disposed in the conduits 252, 254, 256 and 258.

Conduits 260, 262, 264 and 266 are connected to outlet connections in the vessels 236, 238, 240 and 242, respectively, and a residue gas outlet header 268 is connected to the conduits 260, 262, 264 and 266. Valves 270, 272, 274 and 276 are disposed in the conduits 260, 262, 264 and 266. The header 268- is connected to a ballast tank 269 by a conduit 271, and a conventional upstream pressure controller 273 is disconduit 279 is connected to the ballast tank 269 and to.

the suction connection of a conventional gas booster 281. The discharge connection of the gas booster 281 is connected to a conduit 285 having a conventional downstream pressure controller 283 disposed therein.

A closed regeneration gas stream circuit for simultaneously regenerating two of the adsorbent beds contained within the vessels 236, 238, 240 and 242 is provided. A conventional gas stream heater 288 having a heating coil 290 disposed therein is included in the regeneration gas stream circuit. The outlet connection of the heating coil 290 is connected by a conduit 292 to a header 294. A first heated regeneration gas stream inlet head 296 is provided connected to th .ier 294 having a conventional gas stream flow controller 298 disposed therein/The first regeneration gas stream inlet header 296 is connected to the conduits 252, 254, 256 and 258 by conduits 300, 302, 304 and 306 respectively. Valves308, 310, 312 and 314 are disposed in the conduits 300, 302, 304 and 306.'

A second heated regeneration gas stream inlet header 316 is provided connected to the header 294 having a conventional gas stream flow controller 318 disposed therein. The header 316 is connected to the conduits 252, 254, 256 and 258 by conduits 320, 322, 324 and 326 respectively. Valves 328, 330, 332 and 334 are disposed in the conduits 320, 322, 324 and 326. A combined regeneration gas stream outlet header 336 is provided connected to the conduits 260, 262, 264 and 266 by conduits 338, 340, 342 and 344,

respectively. Valves 346, 348, 350 and 352 are dis-' posed in the conduits 338,340, 342 and 344. The combined'regeneration gas stream outlet header 336 is connected to aconventional gas cooler 356 by a conduit 354. The outlet connection of the gas stream cooler '356 is connected to a conventional gas-liquid separator 360 by a conduit 358. The liquid outlet connection of the separator'360 is connected to a conduit 362 having a conventional liquid level control valve 364 disposed therein, and the gas outlet connection of the separator 360 is connected to a conventional gas booster 368 by a conduit 366. The discharge connection of the gas booster 368 is connected to the inlet connection of the heating coil 290 disposed within the heater 288 by a conduit 370. A conduit 372 having a valve 374 disposed therein is connected to the conduit 370 for withdrawing an easy-to-regenerate component product stream from the regeneration gas stream passing through the regeneration gas stream circuit.

A closed cooling gas stream circuit is provided which includes a cooling gas stream inlet header 380 connected to the conduits 252, 254, 256 and 258 by conduits 382, 384, 386 and 388, respectively. Valves 390, 392, 394 and 396 are disposed in the conduits 382,

384, 386 and 388. A cooling gas stream outlet header 398 is provided connected to the conduits 260, 262, 264 and 266 by conduits 400, 402, 404 and 406 respectively. Valves 408, 410, 412 and 414 are disposed in the conduits 400, 402, 404 and 406. The cooling gas stream outlet header 398 is connected to a conventional gas stream cooler 416 which is in turn connected to a conventional gas compressor or gas booster 420 by a conduit 418. The conduit 285, previously described, is connected to the conduit 418. The discharge connection of the gas booster 420 is connected to the cooling gas stream inlet header 380 by a conduit 422.

' OPERATION OF THE SYSTEM 230 By the present invention, as carried out in the system 230, one of the adsorbent beds contained within the vessels 236, 238, 240 and 242 is extensively regenerated over a long cycle time while the other three beds are operated on a short cycle time. The flow patterns of the inlet gas stream, the first heated regeneration gas stream and the cooling gas stream are changed at the beginning of each short cycle so that the three beds are operated in a manner such that one bed adsorbs both easy-to-regenerate and difficult to-regenerate components from the inlet gas stream, one bed is contacted with the first heated regeneration gas stream so that easy-to-regenerate components are desorbed therefrom, and the other bed is contacted with the cooling gas stream. The bed being regenerated on the long cycle is contacted with the second heated regeneration gas stream so that difficult-to-regenerate components are desorbed therefrom. After a predetermined number of short cycles, the bed subjected to extensive regeneration on the long cycle is switched into the short cycle operation, and one of the beds operated on the short cycle which has become loaded with difficult-toregenerate. components is switched into the long cycle operation. Thus, as in the system 10 described above, each of the beds is subjected to extensive regeneration to remove difficult-to-regenerate components adsorbed thereon thereby preventing the buildup of difficult-to-regenerate components on the adsorbent beds.

Referring specifically to FIG. 5, the flow patterns of the various gas streams in the system 230 during a first cycle are shown. Let is be assumed that the adsorbent bed contained within the vessel 236 is contacting the inlet gas stream. The inlet gas stream is conducted to the system 230 by way of the conduit 232 and passes into the inlet gas stream header 234. From the header 234, the inlet gas stream passes by way of conduit 252 'and valve 244 into the vessel236. The conduits 254,

256 and 258, and valves 246, 248 and 250 serve similarly during subsequent cycles. As the inlet gas stream passes through the adsorbent bed contained within the vessel 236, the adsorbable components contained therein are adsorbed on the bed and a residue gas stream substantially free of the adsorbable components is produced. The residue gas stream exits the vessel 236 by way of conduit 260 and valve 270, and passes into the residue gas stream outlet header 268. During subsequent cycles the conduits 262, 264 and 266, and valves 272, 274 and 276 serve similarly. From the header 268,

the residue gas stream passes by way of conduit 271 into the ballast tank 269. From the ballast tank 269 the residue gas stream is withdrawn by way of a conduit 275 from where it is conducted to a point of use or further processing. The operation of the ballast tank 269 and the cooling gas stream make up apparatus connected thereto is identical to the operation of the ballast tank 96 and make up gas apparatus of the system 10, described above.

Let it be assumed that the adsorbent bed within the vessel 238 is being regenerated on the short cycle so stream passes through the adsorbent bed contained within the vessel 238, easy-to-regenerate components are desorbed therefrom into the regeneration gas stream. The regeneration gas stream and desorbed components exit the vessel 238 by way of conduits 262 and 340, and valve 348, and pass into the combined regeneration gas stream outlet header 336. The second heated regeneration gas stream is passed from the second regeneration gas stream inlet header 316 into the vessel 240 by way of conduits 324 and 256, and valve 332. During subsequent cycles, the conduits 320, 252, 322, 254, 326 and 258, and the valves 328, 330 and 334 serve similarly. As the second heated regeneration gas stream passes through the adsorbent bed contained within the vessel 240, difficult-to-regenerate components are desorbed therefrom into the regeneration gas stream. As will be understood, the adsorbent bed within the vessel 240 is contacted with the second regeneration gas stream continuously during the long cycle. The second regeneration gas stream and desorbed components exit the vessel 240 by way of conduits 264 and 342 and valve 350, and pass into the combined regeneration gas stream outlet header 336. Thefirst and second regeneration gas streams and the desorbed easy-to-regenerate and difficult-to-regeneratecomponents are combined in the header 336, and the combined stream passes from the header 336 by way of conduit 354 into the gas cooler 356. While passing through the gas cooler 356, the difficult-to-regenerate components as well as all or part of the easy-toregenerate components are condensed, and the condensed components and combined regeneration gas stream pass by way of conduit 358 into the separator 360. The condensed components are separated from the combined regeneration gas stream within the separator 360 and are removed therefrom by way of conduit 362. The combined regenerationgas stream exits the separator 360 by way of the conduit 366 and passes into the compressor 368. From the discharge of the compressor 368, the combined regeneration gas stream passes into conduit 370. If the easy-to-regenerate components are of the non-condensible type, and as a result, are not condensed in the gas cooler 356, a portion of the regeneration gas stream containing the easy-toregenerate components is removed from the conduit 370 by way of conduit 372. The remaining combined regeneration gas stream passes from the conduit 370 into the heating coil 290 of the heater 288 wherein it is heated to a desired temperature level. From the heating coil 290, the combined regeneration gas stream is passed by way of conduit 292 to the header 294 and the combined stream is divided into the first and second regeneration gas streams by the fiow controllers 298 and 318. That is, a predetermined flow rate of heated regeneration gas is caused to pass into the second heated regeneration gaS stream header 316 and a predetermined flow rate of heated regeneration gas is passed into the first regeneration gas stream inlet header 296.

Let it be assumed that the adsorbent bed within the vessel 242 is being cooled. A cooling, gas stream is passed from the cooling gas stream, inlet header 380 into the vessel 242 by way of conduits'388 and 258, and valve 396. During subsequent cycles, the conduits 252, 382, 254, 384, 256, and 386, and valves 390, 392 and 394 serve similar purposes. The coolihg gas stream exits the vessel 242 by way of conduits 266 and 406 and valve 414, and passes into the cooling gas stream outlet header 398. From the outlet header 39 8, the cooling gas stream is passed through the gas cooler 416 wherein it is cooled, and then to the gas booster 420 by way of conduit 418. Make up gas required to maintain the pressure of the cooling gas stream at a constant level enters the cooling gas stream circuit by way of conduit 285'which is connected to'the conduit 418. The cooling gas stream is circulated from the discharge of the gas booster 420 by way'of conduit 422 back to the cooling gas stream inlet header 380.

As mentioned above, the flow patterns of the inlet gaS stream, the first heated regeneration gas stream and the cooling gas stream are changed at the beginning of each short cycle, while the flow pattern of the second heated regeneration gas stream is changed at the beginning of each long cycle. In order to present a clear understanding of the manner in which the flow patterns of the various gas streams passing through the system 230 are changed, the adsorbent bed and valve sequence for the system 230 through ten short cycles is 

2. The process of claim 1 wherein step (g) comprises the steps of: cooling said regeneration gas stream so that difficult-to-regenerate components contained therein are condensed; separating the condensed difficult-to-regenerate components from the remaining regeneration gas stream; and withdrawing the condensed difficult-to-regenerate components from said process.
 3. The process of claim 2 wherein step (c) comprises: cooling said regeneration gas stream so that easy-to-regenerate components contained therein are condensed; separating the condensed easy-to-regenerate components from the remaining regeneration gas stream; and withdrawing the condensed easy-to-regenerate components from said process.
 4. The process of claim 2 wherein the multi-component inlet gas stream is a natural gas stream, the difficult-to-regenerate components contained therein are pentanes and heavier hydrocarbon compounds, and the easy-to-regenerate components contained therein are butanes and lighter hydrocarbon compounds.
 5. The process of claim 2 wherein the multi-component inlet gas stream is a refinery gas stream, the difficult-to-regenerate components contained therein are heavy olefin hydrocarbon compounds and the easy-to-regenerate components components contained therein are ethylene, ethane and other light hydrocarbon compounds.
 6. An adsorption process for recovering adsorbable components from a multi-component inlet gas stream comprising the steps of: a. contacting one of a plurality of solid adsorbent beds with said inlet gas stream so that adsorbable components which are difficult to regenerate contained therein are adsorbed on said bed and a residue gas stream consisting primarily of adsorbable components which are easy-to-regenerate is produced; b. contacting another of said beds with the residue gas stream produced in step (a) so that easy-to-regenerate components contained therein are adsorbed on said bed and an effluent gas stream substantially free of adsorbable components is produced; c. contacting yet another of said beds with a first heated regeneration gas stream so that easy-to-regenerate components previously adsorbed thereon are desorbed into said regeneration gas stream; d. recovering said easy-to-regenerate components from said first regeneration gas stream; e. contacting still another of said beds with a cooling gas stream so that said bed is cooled; f. continuously changing the flow patterns of said residue gas stream, said first heated regeneration gas stream and said cooling gas stream so that the bed just contacted with said residue gas stream is contacted with said heated regeneration gas stReam thereby desorbing easy-to-regenerate components therefrom, the bed just contacted with said cooling gas stream is contacted with said residue gas stream so that easy-to-regenerate components are adsorbed thereon, and the bed just contacted with said first heated regeneration gas stream is contacted with said cooling gas stream preparatory to again being contacted with said residue gas stream; g. periodically changing the flow pattern of said inlet gas stream so that when the bed contacted therewith becomes loaded with difficult-to-regenerate components, the bed just contacted with said residue gas stream is contacted with said inlet gas stream thereby causing difficult-to-regenerate components to be adsorbed thereon; h. contacting the bed just contacted with said inlet gas stream with a second heated regeneration gas stream during the cycle following step (g) so that the difficult-to-regenerate components adsorbed thereon are desorbed into said second regeneration gas stream; i. recovering the desorbed difficult-to-regenerate components from second regeneration gas stream; and j. repeating steps (f) through (i).
 7. The process of claim 6 wherein step (a) comprises the steps of: cooling said regeneration gas stream so that difficult-to-regenerate components contained therein are condensed; separating the condensed components from the remaining regeneration gas stream; and withdrawing the condensed difficult-to-regenerate components from said process.
 8. The process of claim 7 wherein the multi-component inlet gas stream is a natural gas stream, the difficult-to-regenerate components contained therein are pentanes and heavier hydrocarbon compounds, and the easy-to-regenerate components contained therein are butanes and lighter hydrocarbon compounds.
 9. The process of claim 7 wherein the multi-component inlet gas stream is a refinery gas stream, the difficult-to-regenerate components contained therein are heavy olefin hydrocarbon compounds and the easy-to-regenerate components contained therein are ethylene, ethane and other light hydrocarbon compounds.
 10. The process of claim 7 which is further characterized to include the steps of: passing said produced effluent gas stream into a ballast tank during each cycle when the pressure of said effluent gas stream exceeds a predetermined level; providing make-up gas to said cooling gas stream during each cycle from the effluent gas contained within said ballast tank when the pressure of said cooling gas stream reaches a predetermined minimum level; and withdrawing effluent gas from said ballast tank when the pressure of said effluent gas contained therein exceeds a predetermined level.
 11. An adsorption process for recovering both easy-to-regenerate and difficult-to-regenerate adsorbable components from a multi-component inlet gas stream comprising the steps of: a. contacting one of a plurality of solid adsorbent beds with said inlet gas stream so that both easy-to-regenerate and difficult-to-regenerate adsorbable components contained therein are adsorbed on said bed and a residue gas stream substantially free of such adsorbable components is produced; b. contacting another of said beds with a first heated regeneration gas stream so that previously adsorbed components which are easy-to-regenerate are desorbed into said first regeneration gas stream; c. contacting yet another of said beds with a second heated regeneration gas stream for a period of time at least four times as long as the period of contact of the first heated regeneration gas stream in step (b), to raise the maximum temperature of the effluent from the regenerating adsorber to a temperature at least 50*F higher than the temperature of the effluent from the regenerating adsorber in step (b), so that previously adsorbed components which are difficult-to-regenerate are desorbed into said second regeneration gas stream; d. recovering said easy- and difficult-to-regeNerate components from said first and second regeneration gas streams; e. contacting still another of said beds with a cooling gas stream so that said bed is cooled; f. continuously cycling the flow patterns of said inlet gas stream, said first heated regeneration gas stream and said cooling gas stream so that the bed just contacted with said inlet gas stream is contacted with said first heated regeneration gas stream thereby desorbing easy-to-regenerate components therefrom, the bed just contacted with said cooling gas stream is contacted with said inlet gas stream so that adsorbable components are adsorbed thereon and the bed just contacted with said first heated regeneration gas stream is contacted with said cooling gas stream preparatory to being contacted with said inlet gas stream; g. periodically changing the flow pattern of said second heated regeneration gas stream so that when a bed being contacted with said inlet gas stream reaches a predetermined difficult-to-regenerate component content, it is contacted with said second heated regeneration gas stream and the bed just contacted with said second heated regeneration gas stream is contacted with said first heated regeneration gas stream; and h. repeating steps (f) and (g).
 12. The process of claim 11 wherein step (d) comprises the steps of: combining said first and second regeneration gas streams containing easy and difficult-to-regenerate components respectively; cooling the combined regeneration gas stream so that the easy and difficult-to-regenerate components contained therein are condensed; separating the condensed components from the remaining combined regeneration gas stream; withdrawing the condensed components from said process; heating said combined regeneration gas stream; and dividing said combined heated regeneration gas stream into said first and second heated regeneration gas streams.
 13. The process of claim 11 wherein the multi-component inlet gas stream is a natural gas stream, the difficult-to-regenerate components contained therein are pentanes and heavier hydrocarbon compounds, and the easy-to-regenerate components contained therein are butanes and lighter hydrocarbon compounds.
 14. The process of claim 11 wherein the multi-component inlet gas stream is a refinery gas stream, the difficult-to-regenerate components contained therein are heavy olefin hydrocarbon compounds and the easy-to-regenerate components contained therein are ethylene, ethane, and other light hydrocarbon compounds.
 15. The process of claim 6 which is further characterized to include the steps of: passing said residue gas stream substantially free of adsorbable components into a ballast tank during each cycle when the pressure of said residue gas stream exceeds a predetermined level; providing make-up gas to said cooling gas stream during each cycle from the residue gas contained within the said ballast tank when the pressure of said cooling gas stream reaches a predetermined minimum level; and withdrawing residue gas from said ballast tank when the pressure of said residue gas contained therein exceeds a predetermined level.
 16. A cyclic adsorption process for recovering adsorbable components from a multi-component inlet gas stream which comprises the steps of: a. contacting one of a plurality of solid adsorbent beds with said inlet gas stream so that adsorbable components contained therein which are difficult to regenerate are adsorbed on said bed and a residue gas stream consisting primarily of components which are easy to regenerate is produced; b. contacting another of said beds with a first heated regeneration gas stream so that difficult-to-regenerate components previously adsorbed thereon are desorbed into said first regeneration gas stream; c. recovering said difficult-to-regenerate components from said first regeneration gas stream; d. contacting yet another of said beds with a first cooling gas stream so that sAid bed is cooled preparatory to contacting said inlet gas stream; e. continuously cycling the flow patterns of said inlet gas stream, said first heated regeneration gas stream and said first cooling gas stream on a long cycle so that the bed just contacted with said inlet gas stream is contacted with said first heated regeneration gas stream thereby desorbing difficult-to-regenerate components therefrom, the bed just contacted with said first cooling gas stream is contacted with said inlet gas stream so that difficult-to-regenerate components are adsorbed thereon and the bed just contacted with said first heated regeneration gas stream is contacted with said cooling gas stream; f. contacting still another of said beds with the residue gas stream produced in step (a) so that easy-to-regenerate components and remaining difficult-to-regenerate components contained therein are adsorbed on said bed and an effluent gas stream substantially free of adsorbable components is produced; g. contacting still another of said beds with a second heated regeneration gas stream so that easy-to-regenerate components previously adsorbed thereon are desorbed into said second regeneration gas stream; h. recovering said easy-to-regenerate components from said second regeneration gas stream; i. contacting still another of said beds with a second cooling gas stream so that said bed is cooled preparatory to contacting said residue gas stream; j. continuously cycling the flow patterns of said residue gas stream, said second heated regeneration gas stream and said second cooling gas stream on a short cycle so that the bed just contacted with said residue gas stream is contacted with said second heated regeneration gas stream thereby desorbing easy-to-regenerate components therefrom, the bed just contacted with said second cooling gas stream is contacted with said residue gas stream so that easy-to-regenerate components and remaining difficult-to-regenerate components contained therein are adsorbed thereon and the bed just contacted with said second heated regeneration gas stream is contacted with said second cooling gas stream; and k. changing the flow patterns of said inlet gas stream and said residue gas stream at the beginning of each long cycle so that the bed just contacted with said second cooling gas stream is contacted with said inlet gas stream and the bed just contacted with said first cooling gas stream is contacted with said residue gas stream thereby subjecting each of said beds to regeneration on said long cycle so that adsorbed difficult-to-regenerate components are removed therefrom.
 17. The process of claim 11 wherein step (c) comprises the steps of: cooling said first regeneration gas stream so that difficult-to-regenerate components contained therein are condensed; separating the condensed components from the remaining first regeneration gas stream; and withdrawing the condensed difficult-to-regenerate components from said process.
 18. The process of claim 17 wherein step (h) comprises the steps of: cooling said second regeneration gas stream so that easy-to-regenerate components contained therein are condensed; separating the condensed components from the remaining second regeneration gas stream; and withdrawing the condensed easy-to-regenerate components from said process.
 19. The process of claim 17 wherein the multi-component inlet gas stream is a natural gas stream, the difficult-to-regenerate components contained therein are pentanes and heavier hydrocarbon compounds, and the easy-to-regenerate components contained therein are butanes and lighter hydrocarbon compounds.
 20. The process of claim 17 wherein the multi-component inlet gas stream is a refinery gas stream, the difficult-to-regenerate components contained therein are heavy olefin hydrocarbon compounds and the easy-to-regenerate components contained therein are ethylene, ethane and other light hydrocarbon compounds.
 21. The process oF claim 17 which is further characterized to include the step of: passing said produced effluent gas stream into a ballast tank during each cycle when the pressure of said effluent gas stream exceeds a predetermined level; providing make-up gas to said cooling gas stream during each cycle from the effluent gas contained within said ballast tank when the pressure of said cooling gas stream reaches a predetermined minimum level; and withdrawing effluent gas from said ballast tank when the pressure of said effluent gas contained therein exceeds a predetermined level. 